Can 3D shape-from shading be a marker of post-stroke recovery?

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Marjola Peca¹ (mrp18fqc@bangor.ac.uk), Ayelet Sapir¹, Giovanni d'Avossa¹; ¹Bangor University

To perceive depth in 2D images, the visual system relies on monocular cues such as shape-from-shading, where shading is interpreted relative to an assumed light source. Typically, objects with brighter tops are perceived as convex and those with darker tops as concave, reflecting the assumption that light comes from above. Research consistently shows a leftward bias in the assumed lighting direction, possibly linked to right-hemisphere dominance in shape-from-shading processing. Interestingly, post-stroke survivors with left spatial neglect exhibit a different bias in the acute stage compared to age-matched healthy individuals, suggesting that shape-from-shading perception may be influenced by spatial attention. This study investigates whether a simple 3D shape-from-shading task can serve as a marker of spatial neglect recovery in post-stroke survivors. We are conducting a longitudinal study on individuals with right-hemisphere strokes and left-sided neglect, assessing them at two time points: upon admission to a rehabilitation clinic and before discharge. Participants complete the Montreal Cognitive Assessment (MoCA), a bell cancellation task, and a 3D shape-from-shading judgment task. To evaluate whether performance on the 3D task reflects recovery, we compare bias differences between sessions. We then examine associations between the 3D task, MoCA, and the bell cancellation task to determine whether changes are specific to spatial attention or broader cognitive function. Our findings will show whether perceptual biases in shape-from-shading can serve as markers of visuospatial recovery in stroke patients, potentially informing future diagnostic and rehabilitative strategies.

Topic Area: ATTENTION: Spatial